The broad objective of this study is to elucidate the strategy of the Epstein-Barr virus (EBV), particularly as it relates to the persistence of the virus, unrecognized by the immune system, during the entire lifetime of seropositive individuals. Our findings suggest that small heavy B- lymphocytes may harbor the latent viral genome. We shall study the expression of the viral genome in these cells, in comparison with its malignant counterpart, Burkitt's lymphoma, and in contrast to the acutely infected, proliferating blast population in vitro (LCL) and in vivo (immunoblastic EBV-carrying lymphomas in immuno-defectives). The findings are expected to elucidate the regulation of viral expression, the immunogenicity of different viral products, and the occurrence of cell phenotype dependent modulations n viral transcription. Considered together with our parallel work on the Ig/myc translocation, this work will also contribute to the understanding of Burkitt lymphoma development. A special subproject concerns the interactions of the virus with epithelial cells, in view of its documented association with nasopharyngeal carcinoma.